Service providers typically provide numerous voice and/or data services to subscribers using wireline and/or wireless communication networks. Exemplary services include cellular telephony, access to the Internet, gaming, broadcasting or multicasting of audio, video, and multimedia programming, etc. Mobile devices, such as cell phones, personal data assistants, smart phones, pagers, text messaging devices, global positioning system (GPS) devices, network interface cards, notebook computers, and desktop computers, may access the services provided by the communication networks over an air interface with one or more base stations. Communication between the mobile devices and base stations is governed by various standards and/or protocols, such as the standards and protocols defined by the 3rd Generation Partnership Project (3GPP, 3GPP2).
Network operators use offline and online charging functions to keep track of the charges incurred by each mobile device for accessing the various services. The 3GPP/3GPP2 standards groups have defined a set of specifications that may be used to implement online charging systems and offline charging systems to cover charging in the various network domains (e.g., a circuit-switched network domain, a packet-switched network domain, and/or a wireless domain), IP multimedia subsystems (IMS), and emerging 3G/OMA application services.
Online charging is generally defined as a charging mechanism where charging information can affect the service rendered in real-time, and therefore a direct interaction of the charging mechanism with session/service control is needed. In online charging, charging information for network resource usage is collected concurrently with the resource usage (to provide a service). However, authorization for the network resource usage is obtained by the network prior to the actual resource usage. The network elements in a communication network include Charging Trigger Functions (CTF). For online charging, the CTF triggers on charging events, collects charging information pertaining to the charging events, and assembles the charging information into matching charging events. The CTF then transmits credit requests to the Online Charging System (OCS) to obtain authorization for the charging event/network resource usage requested by the end user. The CTF delays the actual resource usage until permission has been granted by the OCS. When a granted quota of service units is obtained from the OCS, the CTF in the network element allows resource usage to begin and performs budget control during the resource usage. The CTF enforces termination of the end user's resource usage when permission by the OCS is not granted or expires.
There are a variety of types of networks operable to provide voice and data communications for mobile users. One present project within the 3GPP is the Long Term Evolution (LTE) which is a project to improve the UMTS mobile phone standard to cope with future requirements. The architecture defined by this project is referred to as the Evolved Packet System (EPS). The EPS architecture comprehends E-UTRAN (Evolved UTRAN) on the access side and EPC (Evolved Packet Core) on the core side. The LTE/EPC network includes a variety of network elements, some of which include a serving gateway (S-GW), a packet data network gateway (PDN-GW), an HRPD serving gateway (HSGW), a AAA proxy server, and a policy and charging rule function (PCRF).
LTE/EPC network allows for roaming between a home network and one or more visited networks. Roaming is a general term in mobile communications that refers to the extending of service in a location that is different from the home location where the service was registered. There are two types of roaming in LTE/EPC networks: home roaming and local roaming. For home roaming, the S-GW is located in the visited network, but the PDN-GW is located in the home network. When the end user begins to use a service in the visited network, the S-GW in the visited network will route data traffic back to the PDN-GW in the home network. Thus, services are still provided via the PDN-GW in the home network. For the local roaming however, both the S-GW and the PDN-GW are located in the visited network. When the end user starts to use a service, the S-GW in the visited network directly routes data traffic to the PDN-GW in the visited network. Thus, services are provided via the PDN-GW in the visited network.
In the present market deployment, the local roaming model is not widely deployed because it is not clearly defined how the operator of the home network charges for services provided in the visited network. The 3GPP standards (e.g., 3GPP TS 32.820) still simply follow the existing home roaming charging model, which does not work well for the local roaming scenario.